Quality of Feather Meal as Affected by Feather Processing Conditions ,

Feather meal contains three sulfur amino acids: cystine, lanthionine, and methionine. Procedures were investigated to determine the best conditions for quantitating the sulfur amino acids in feather meal. To separate the sulfur amino acids by ion exchange chromatography, an elution system using 100 mM citrate buffer at pH 3.5 was found to be acceptable. Performic acid oxidation followed by acid hydrolysis oxidized lanthionine but also cleaved a substantial portion to form cysteic acid and an unknown compound. This result suggested that samples containing lanthionine should not be oxidized before hydrolysis. The effects of pH and of pressure during feather processing were determined. The pH was 5,7, or 9; and the steam pressures were 207, 276, or 345 kPa for 30 min. Increasing the pH or pressure increased the percentage of the protein that was pepsin digestible. As the pepsin digestibility increased, the cystine content of the feather meal decreased and mat of lanthionine increased. The experimental feather meals were included at 2.5% in a diet low in sulfur amino acids. The preparation of the feather meal had no effect on the feed:gain ratio or on weight gains by the chicks.